Approximately 80% of residents in long term care institutions have osteoporosis and the incidence of hip or vertebral fractures is 8-9 times that in the community. Although there are FDA approved therapies for osteoporosis, based on younger women, recent studies demonstrate that oral bisphosphonates and hip pads are not effective in this frail cohort. It is not known it treatment failures are due to ineffective medication, poor compliance, or nonskeletal factors. Prior to a large fracture reduction study, a pilot study is critically needed to examine safety and efficacy. We postulate that in frail, institutionalized elderly women, a single dose of intravenous zoledronic acid will: 1) be efficacious as demonstrated by maintenance or improvements in conventional bone mass and reductions in bone turnover, 2) be safe and feasible, 3) provide estimates for fracture reduction in this cohort for use in planning a future study. To address these hypotheses, we will enroll 180 institutionalized women in a 2-year, calcium-vitamin D controlled, randomized, double-blind trial of a single dose of intravenous bisphosphonate, zoledronic acid. The intravenous therapy omits concerns regarding poor oral absorption or patient compliance. Participants will reside in the long term care settings associated with the Division of Geriatric Medicine, University of Pittsburgh. Outcome measures will include bone density of the spine and hip, markers of bone turnover, vertebral x rays to assess for fractures and adverse events. Eleven nursing homes in the Pittsburgh area have agreed to participate. The PI is one of a handful of physicians trained in endocrinology and geriatric medicine, who previously conducted nursing home research on osteoporosis. This study will provide the necessary data on the efficacy and safety of osteoporosis treatment in elderly women with a feasible single dose of intravenous antiresorptive agent, and will lay the foundation for a future multicenter fracture reduction trial in this cohort. Public Health Relevance: Osteoporosis is common in nursing home residents, yet most are neither diagnosed nor treated. This study will examine the effectiveness and safety of a single dose intravenous therapy for osteoporosis in this frail, often neglected group.